Apparatus and method for re-synthesizing signals

ABSTRACT

The disclosed embodiments relate to an apparatus and a method for re-synthesizing signals. The apparatus includes a receiver for receiving a plurality of digitally multiplexed signals, each digitally multiplexed signal associated with a different physical transmission channel, and for simultaneously recovering from at least two of the digital multiplexes a plurality of bit streams. The apparatus also includes a transmitter for inserting the plurality of bit streams into different digital multiplexes and for modulating the different digital multiplexes for transmission on different transmission channels. The method involves receiving a first signal having a plurality of different program streams in different frequency channels, selecting a set of program streams from the plurality of different frequency channels, combining the set of program streams to form a second signal, and transmitting the second signal.

This application claims the benefit under 35 U.S.C. §119 of aprovisional application 60/677563 filed in the United States on May 4,2005.

FIELD OF THE INVENTION

The present invention generally relates to communications systems. Morespecifically, the present invention relates to the receiving andretransmission of content within a communications system.

BACKGROUND OF THE INVENTION

This section is intended to introduce the reader to various aspects ofart, which may be related to various aspects of the present inventionthat are described and/or claimed below. This discussion is believed tobe helpful in providing the reader with background information tofacilitate a better understanding of the various aspects of the presentinvention. Accordingly, it should be understood that these statementsare to be read in this light, and not as admissions of prior art.

In today's data communication systems such as used in satellite TV, dataof different types often reside in what are known as virtual channels.The data from these virtual channels is separately disassembled intodata packets, aggregated within and across different data types into bitstreams and conveyed by packet delivery systems. Data consumerappliances, such as satellite receivers, select from physical channelsavailable to them, convert the signals on these channels to digital form(packets) and collect the data packets required to re-assemble thedesired virtual channels of information (e.g., audio, video, programguide, transactional data, etc.). At different points along the datapath between a content provider and a content consumer data managementopportunities occur. A piece of data may come from one of many sources,be routed through one of many satellites, pass through several of manytransponders aboard the satellite, be received by a consumer antenna,and be distributed to places of consumption.

Consumer receivers are often capable of receiving only one of thephysical channels from the satellite at a time for display. However, newreceivers may contain advanced features the consumer can use. Forinstance, a receiving device may contain more than one tuner for use ineither two picture simultaneous display systems or content recording.Additionally, consumer households often include multiple receivers, eachreceiver requiring the tuning of one or more channels for use.

The ever-expanding amount of content for delivery has made it verydifficult to deliver that content to all places at all times. Systemsreceiving data from up to four separate satellites to deliverprogramming is to the home can no longer deliver all of the content onone coaxial cable connection. Various approaches have been adaptedincluding the use of multiple cables or complex switching arrangements.Many of these approaches are in some manner suboptimal for a homeinstallation due to high cost or high complexity.

Another solution may be to employ a system of preselecting, combining,and redistributing the incoming content based on the physical channelsrequested by the user(s) using analog signal processing. As a result,only the content required for delivery to the receivers in a householdare selected from the initial available content. The desired content maythen be provided on a single cable that is relatively easy to distributearound the household. The solution relies on coarse analog signal tuningand re-mixing to move channels or frequency regions of signals from anoriginal spectral location in frequency at the input to another spectrallocation in frequency on a common signal at the output. Further,channels or signal regions at the same frequency but on differentsatellites may be combined by moving one or both of the originalchannels or regions. These relocated signals containing the desiredchannels are then provided on the single cable, eliminating the need forany additional switching and multiple cable connections.

The analog solution involving preselection, combination, andredistribution remains limited in the number of channels that can beprovided due to the inherent shortcomings of performing the processingin the analog domain. Narrow band filters used to select individualphysical channels while rejecting others are impractical at frequenciesabove the range of one gigahertz (GHz). Available filters having apractical bandwidth require additional channel separation in order toprevent undesired interferences in the output signal. Additionally asthe desire to deliver more requested channels to the home increases, thesubsequent increase in analog circuit complexity results in an expensiveand inefficient design with potential problems due to analog crosstalk.Further, the analog solution does not include additional capabilitiesinvolving channel data re-mulitplexing that may prove useful. Theability to manipulate the data streams in the digital domain increasesthe value and feature set of the network. Therefore, an apparatus andprocess for receiving and re-synthesizing of channels for distributionin a more optimal manner is desired.

SUMMARY OF THE INVENTION

The present invention relates to an apparatus and a method forre-synthesizing signals. The apparatus includes a receiver for receivinga plurality of digitally multiplexed signals, each digitally multiplexedsignal associated with a different physical transmission channel, andfor simultaneously recovering from at least two of the digitalmultiplexes a plurality of bit streams. The apparatus also includes atransmitter for inserting the plurality of bit streams into differentdigital multiplexes and for modulating the different digital multiplexesfor transmission on different transmission channels.

The method involves receiving a first signal having a plurality ofdifferent program streams in different frequency channels, selecting aset of program streams from the plurality of different frequencychannels, combining the set of program streams to form a second signal,and transmitting the second signal.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a block diagram of an exemplary system using the presentinvention.

FIG. 2 is a block diagram of an embodiment of the present invention

FIG. 3 is a block diagram of another embodiment of the presentinvention.

FIG. 4 is a block diagram of yet another embodiment of the presentinvention.

FIG. 5 is a block diagram of yet another embodiment of the presentinvention.

FIG. 6 is a block diagram of a further embodiment of the presentinvention.

FIG. 7 is a flow chart illustrating a method of the present invention.

The characteristics and advantages of the present invention may becomemore apparent from the following description, given by way of example.

DETAILED DESCRIPTION

One or more specific embodiments of the present invention will bedescribed below. In an effort to provide a concise description of theseembodiments, not all features of an actual implementation are describedin the specification. It should be appreciated that in the developmentof any such actual implementation, as in any engineering or designproject, numerous implementation-specific decisions must be made toachieve the developers' specific goals, such as compliance withsystem-related and business-related constraints, which may vary from oneimplementation to another. Moreover, it should be appreciated that sucha development effort might be complex and time consuming, but wouldnevertheless be a routine undertaking of design, fabrication, andmanufacture for those of ordinary skill having the benefit of thisdisclosure.

It is noted that familiarity with television broadcasting and receiversis assumed and is not described in detail herein. For example, otherthan the inventive concept, familiarity with current and proposedrecommendations for TV standards such as National Television SystemsCommittee (NTSC), Phase Alternation Lines (PAL), Sequential Couleur AvecMemoire (SECAM), Advanced Television Systems Committee (ATSC), andDirect Broadcast Satellite (DBS) is assumed. Likewise, other than theinventive concept, transmission concepts such as satellite transponders,down-link signals, eight-level vestigial sideband (8-VSB), QuadratureAmplitude Modulation (QAM), and receiver components such as aradio-frequency (RF) front-end, or receiver section, such as a low noiseblock, tuners, and demodulators is assumed. Similarly, formatting andencoding methods (such as Moving Picture Expert Group (MPEG)-2 SystemsStandard (ISO/IEC 13818-1)) for generating transport bit streams arewell-known and not described herein. In addition, the inventive conceptmay be implemented using conventional programming techniques which, assuch, will not be described herein.

The following describes a circuit used for processing satellite signals.Other systems utilized to receive and transmit other types of signalswhere the signal input may be supplied by some other means may includevery similar structures. Those of ordinary skill in the art willappreciate that the embodiment of the circuits described herein ismerely one potential embodiment. As such, in alternate embodiments, thecomponents of the circuit may be rearranged or omitted, or additionalcomponents may be added. For example, with minor modifications, thecircuits described may be configured to for use in non-satellite videoand audio services such as those delivered from a cable network.Further, the re-synthesizer described could be used in conjunction witha home networking system. The re-synthesizer may receive inputs from asatellite or cable network, process them, and provide them as an outputto the home network system. The output may in the form of a wired orwireless transmission.

Turning now to the drawings and referring initially to FIG. 1, anoverall block diagram 100 of a system using the present invention isshown. FIG. 1 represents a typical satellite system installation at acustomer home. A similar installation may also exist at an apartmentcomplex or hotel where the system may be augmented with additionalequipment often incorporated in multi-dwelling unit applications.Satellite transponders located on satellites 102 a-c transmit satellitesignals to satellite dishes 104 a-c. Each satellite dish contains areflector, a feed horn and a low noise block converter (LNB).

Each of the satellite signals may represent one or more individualphysical channels. Each of the physical channels may in turn representone or more preferably digital bit streams of information combinedtogether as a digital multiplex, encoded, and modulated using variousanalog and/or digital modulation techniques. The digital data streamsare usually called program streams and may be streams of audio, video,or other data including program guide information. The physical channelsare often grouped to cover a limited frequency range such as 500 to 1000MHz of bandwidth. The satellite signals are often located in themicrowave frequency range, for instance 11-13 Gigahertz (GHz). The LNBsin the satellite dishes 104 a-c will amplify and convert the satellitesignal in the 11-13 GHz range to an L-band signal in the 1-2 GHzfrequency range. Although three satellite dishes are shown, the orbitallocations of the satellites 102 a-c may permit using one satellite dishcontaining one reflector and three feed horns and LNBs. Also, systemsmay utilize more. or fewer than the three satellites signals illustratedhere. The systems may additionally use techniques such as polarizationdiversity to increase the number of satellite signals delivered fromeach satellite.

Each of the three L-band signals from the satellite dishes 104 a-c areprovided through separate coaxial cables to a re-synthesizer 110. Thethree L-band signals in their entirety cannot be supplied through asingle coaxial cable for delivery into the customer home, because theL-band signals occupy too much frequency bandwidth. As previouslydescribed, each L-band signal may occupy 1 GHz of bandwidth, and atypical customer premises cable installation may only support less than2 GHz of total signal bandwidth. The re-synthesizer 110 extracts certainranges of frequencies containing selected physical channels as portionsof the three L-band signals provided. The re-synthesizer 110 alsofrequency translates the extracted ranges as needed and re-combines themto form a new single selected L-band signal. The process used by there-synthesizer 110 may be described as a preselection of certainphysical channels. However, the process used by the re-synthesizer 110is different from a direct tuning of those certain physical channelssince other energy besides the selected channel may be present, and thechannels are then recombined to form a new signal for furtherdistribution. Further, the re-synthesizer 110 also provides processingto recover the individual program streams from the physical channelspresent. The re-synthesizer 110 may also allow adding or removing ofstreams as well as re-arrangement of streams to form new physicalchannels of information. Note that the FTM 110 may reside physicallyoutside the customer home as shown, or may reside very near to the entrypoint into the customer home or a multi-dwelling unit. For example, there-synthesizer may be located in a room adjacent to the entry point forthe cabling from the satellite dishes 104 a-c. The room may includeadditional control devices for use with the network and there-synthesizer 110.

Once the re-syhthesizer 110 has preselected and processed the physicalchannels for use, the selected signal is provided over a single coaxialcable to the customer's premises 120. The selected signal may passthrough a set of signal splitters 122 a-c, as needed, to supply each ofthe locations for the premises installation. The splitters 122 a-c maycontain passive circuits such as transformers and resistors or may alsocontain amplifiers in order to increase the signal level at theinstallation location.

At each installation location in the premises 120, the selected signalis provided to a standalone terminal 130 or to a combination settop box140 a-c and display device 150 a-c. The terminal 130 and settop box 140a-c operate in a similar manner. Each of them receive the selectedsignal, tune to the desired physical channel within the selected signal,demodulate the physical channel to produce a transport stream, andextract the desired bit stream(s) from the transport stream. Theterminal 130 may be used for local storage of various bit streams or fordistribution of these bitstreams over a different network such as awireless network or an Ethernet connection. The settop box 140 a-cconverts the desired bitstream(s) into video and audio signals fordisplay on the display device 150 a-c.

The terminal 130 and settop boxes 140 a-c may provide one or morecontrol signals back onto the cable to the re-synthesizer 110. Thecontrol signal is generated based on inputs provided, for instance by acustomer. The control signal sent to re-synthesizer 110 containsinformation necessary to perform the preselection and processing offrequency ranges, physical channels; and program streams from each ofthe L-band signals. The communication protocol to the re-synthesizer 110may be done in a manner suitable for delivery as is known in the art,such as frequency shift keying FSK protocol. The control signal mayalternately be supplied through a wireless link. Electrical power mayalso be passed through the coaxial cable to the re-synthesizer 110 andfurther on to the satellite dishes 104 a-c.

As described earlier, a conventional re-synthesizer, sometimes known asa frequency translation module, contains analog signal processing usedfor the filtering, mixing, and recombining of the L-band signals. Analogsignal processing contains limitations when operating at highfrequencies in the 1 GHz range, and the complexity of the analog signalprocessing increases significantly with an increase of the number ofselected physical channels. The utilization of digital signal processingwithin the re-synthesizer structure permits greater flexibility andremoves some of the limitations of analog signal processing. The digitalprocessing further permits recovery and processing of the programstreams permitting additional flexibility and efficiency.

Turning now to FIG. 2 a block diagram 200 of an embodiment of thepresent invention is shown. The diagram shows an implementation of there-synsthesizer 110 that includes digital signal processing in order toincrease the performance and available bandwidth for selected channels.In order to facilitate a further understanding of the invention, are-synthesizer 110 will be described here using only a single L-bandsignal as an input. Further, the re-synthesizer 110 described here willinclude the capabilities only to translate frequency ranges or physicalchannels from the input to the output. The single L-band signal, as ananalog input, is processed through an RF processing block 210. The RFprocessing block 210 may contain circuitry for filtering undesiredenergy outside the signal frequency range, may correct for any frequencyresponse errors introduced, and may amplify the signal to a levelnecessary for input to the analog to digital (A/D) converter 220. Theinput RF processing block 210 may also contain any mixing circuitsnecessary to position the L-band signal in the correct frequency rangefor operation of the A/D converter 220.

The A/D converter 220 digitizes the processed L-band signal into aseries of samples, each sample containing a group of bits. In anexemplary embodiment, the processed satellite signal is located betweenthe frequencies of 975 and 1425 MHz. The A/D converter 220 samples theprocessed L-band signal at a rate of 933 megasamples per second (MSPS)generating a digital signal containing a series of samples, each samplerepresented by 8 bits. The A/D converter 220, may also generate atranslated frequency image of the L-band signal essentially translatingthe signal from an initial frequency range in the analog domain to adifferent frequency range based on sampling principles. A clock signal,not shown, is supplied to the A/D converter for performing the sampling.The clock signal may be generated by a crystal or as part of a voltagecontrolled oscillator. The clock signal may also directly, or throughadditional multipliers and dividers, supply signals to other blockswithin the re-synthesizer 110.

The digital channel selector 230 receives the sampled signal andproceeds to select and down-convert each of the individual physicalchannels that have been selected. After processing, each of the selectedindividual channels are located within the same frequency range at ornear to baseband, but are contained as individual signals on separatesignal lines. The number of bits representing each selected individualchannel may be different from the original sampled signal based on theprocessing method employed. The use of digital signal processing andprocessing of the signal in parallel permits narrower filteringconstraints and more efficient channel selection within there-synthesizer 110.

Each of the individual selected channels is provided to the digitalchannel re-combiner 240. The digital channel re-combiner 240 frequencytranslates the individual selected channels each to a different andseparate frequency range and combines these signals together to form asingle selected digital signal. The selected digital signal is suppliedto a digital to analog (D/A) converter 250. The D/A converter 250converts the selected digital signal to a selected analog signal. In apreferred embodiment, the selected digital signal provided to the D/Aconverter 250 is a series of 10 bit samples at a rate of 950 MSPS. TheD/A converter 250 outputs a selected analog signal within a frequencyrange of DC to 475 MHz.

The selected analog signal is passed to the RF processing block 260. TheRF processing block 260 provides any analog signal processing necessaryto properly send the selected analog signal on the coaxial cable to thecustomer home. The RF processing block 260 may contain circuitry forfiltering undesired signal energy outside the signal frequency range,such as the images produced by the sampling process in D/A converter250. The RF processing block 260 may also correct for any otherfrequency response errors introduced, and may amplify the signal asnecessary to provide the signal onto a coaxial cable. The RF processingblock 260 may also contain a mixing circuit necessary to position theselected analog signal in the correct L-band frequency range, forinstance 975-1425 MHz.

Some additional circuitry may also be included such as for controllingthe blocks, receiving and processing user inputs, and additional signalprocessing, although this circuitry is not shown here.

Turning now to FIG. 3, an illustrative block diagram of a circuit 300 ofan embodiment of a portion of the present invention is shown. Circuit300 represents circuitry contained with the digital channel converterblock 230. A sampled signal, converted from an L-band signal by A/Dconverter 220, is provided to the sample demultiplexer 310. Sampledemultiplexer 310 resamples at a demultiplexer sampling rate, F_(F), (orpost-decimation sampling rate) to provide a number of decimated samplestreams in parallel.

Each of the decimated sample streams represents a sampled and timeshifted version of the original signal with each of the folded spectra,from the decimation, aliased into the same decimated frequency space.The number of decimated sample streams, N, may be integrally related tothe number of virtual channels in the original signal. In a preferredembodiment, the number of physical channels is sixteen. Further, thesample demulitplexer 310 sampling rate is preferably two times the datarate of one of the physical channels, or F_(F)=2F_(S) where F_(S) is thedata rate of the physical channel. Each of the decimated sample streamspasses through a sampling interface block 320. The sampling interfaceblock 320 provides any sampling domain adjustments necessary in movingthe signal from the A/D converter 220 and sample demulitplexer 310 tothe filter bank 330 a-N, connected to the sampling interface block 320.The filter bank 330 a-N may provide a number of process steps includingfiltering the physical channels that are distributed within thedecimated sample streams prior to the physical channels being separated.The filtering provides rejection of any energy not within a physicalchannel while generating a reconstructive set of base signals forselecting out the physical channels in further downstream processing.The filter bank 330 a-N may also provide a time realignment of each ofthe decimated sample streams. In a preferred embodiment, the filter bank330 a-N consists of a bank of bifurcated filters that collectivelygenerate a filtered signal vector. Since all the bifurcated filters havea similar structure, only one bifurcated filter is described in detailherein.

A bifurcated filter may typically consist of two parallel branches ofcoefficient multiply and delay operations with the operations in each ofthe branches separately summed together. Each branch is designated aseither an even output signal or an odd output signal. The number ofmultiply and delay operations in each branch may vary based on designcriteria. For instance, sixteen weighted multiply and a number ofcoefficient multipliers may be used in each bifurcated filter. The delayelement is controlled by a decimated sample clock signal, not shown, ata frequency F_(f). The summing node separately adds together thosevalues from each of the odd weighted multipliers and even weightedmultipliers to form the odd and even output signal. The orientation ofthe filter branches and operations within the branches allows specialproperties to exist. These properties include amplitude inversion of thesignal or time reversing the signal within the branch. As noted, otherfilter structures may be used, as known to those skilled in the art, inconjunction with the various techniques of simultaneous channelreception techniques.

The output signal, a filter signal vector containing 2N signal streams;from the filter bank 330 a-N connects to a bank of summing nodes 340a-N. Referring to the preferred embodiment, the even and odd outputsfrom each of the different bifurcated filters may be combined in across-coupling pattern. The even output of filter 0 is summed with theodd output of filter N-1, even output of filter 1 with the odd output offilter N-2, and so on as shown. The summing nodes 340 a-N generate a setof filtered sample streams.

The filtered sample streams at the output of summing nodes 340 a-Nconnect to a distributor block 350. The main purpose of the distributorblock 350 is to process the filtered sample streams generated by thefilter block 330 a-N and summing nodes 340 a-N to reconstruct the set ofphysical channels, originally provided in the L-band signal, from thedecimated and filtered sample streams. The processing may includerecombining the streams in a manner using mathematical operations. In apreferred embodiment the distributor block 350 uses a type IV DiscreteCosine Transform (DCT) for processing the filtered sample streams. Thebifurcated filter structure described previously further permits a smallDCT structure in implementation by making use of the inversion and timereversal properties of the filter. The bifurcated filter structure mayalso permit use of a DCT employing a sparse matrix decompositionstructure.

The combination of the filter bank 330 a-N, summing node 340 a-N, anddistributor 350 results in generating a set of output streams, eachrepresenting the separated data content from a physical channel. The setof individual physical channels from the distributor 350 are generatedfrom the set of decimated sample streams where each stream containscontent from each of the physical channels in a sample aliasedcondition. It should be noted that other methods may be employed foraccomplishing recovery of separate physical channels simultaneously froma single signal.

The output of distributor block 350 represents N individual physicalchannels positioned at or near to baseband frequency. Each physicalchannel, in digital signal form, may be located on a separate signalline at the output of distributor block 350. Each of the separate signallines connect to a channel selector block 360. The channel selectorblock 360 may select a set of physical channels from the original Ninput channels provided. Any number of channels up to the full number Nmay be selected. For instance, four channels may be selected. The numberof channels permitted for selection in channel selector block 360 is adesign choice, and the full number of permitted channels for selectiondoes not have to be selected at any one time. Additionally, any furtherphysical channel separation may be performed, such as removing anyaliasing components present due to the complex form of the signal as aresult of the previously described processing.

The channel selector block 360 receives inputs from a controller 370regarding which, if any, of the originally received physical channels iscurrently requested by the customer. The controller 370 may connect tothe sample demultiplexer 310, interface 320, filter bank 330 a-N, anddistributor 350 in addition to connecting to channel selector 360. Thecontroller 370 may also provide an interface for user inputs or acommunications input in order to receive and convey the user requestedchannel information from multiple locations. As described previously,the user inputs may be supplied through the signal cable or through someother communications means. Also, as described previously, a home orcustomer premises may supply more than one customer input. In addition,controller 370 may provide additional functions for operation of thedemultiplexer 310, interface 320, filter bank 330 a-N, and assembler350, such as clock functions, as necessary. The controller 370 may alsobe embodied as a portion of a larger controller function responsible forcontrolling and managing, for instance, the entire FTM device.

Turning now to FIG. 4, a block diagram 400 of a further embodiment ofthe present invention is shown. FIG. 4 illustrates an implementation ofthe digital channel re-combiner 240. The M outputs, representing a setof selected physical channels, of channel selector 360 are provided tothe assembler 410. As described previously, the M outputs of the channelselector 360 may be equal to or less than the N physical channelspresent in the original L-band signal. In a preferred embodiment, theassembler 410 may receive up to N inputs. If the number of signalsprovided from channel selector 360 is less than N, the remaining inputsof channel assembler 410 are placed in a condition of “null” or noinput. Additionally, the assembler 410 may also provide the ability tore-order the M input signals. For instance, if the M signals provided tothe assembler 410 are physical channels in positions 1, 2, 3, and 4 fromselection of the original N channels, the assembler 410 may re-positionthe M signals by addressing them as inputs 1, 5, 9, and N-1. In thismanner, further processing, including internal or external filtering maybe simplified. Also, the re-positioning permits re-spacing of the Msignals.

The assembler 410 provides processing for converting the selectedchannels into a set of signals forming a base set of parallel datastreams that can then be filtered prior to remultiplexing and convertingto an analog signal. The channel re-combiner 410 provides N outputs as aset of converted sample streams to inverse filter bank 420 a-N. Theinverse filter bank 420 a-N provides filtering and/or time delayoperations necessary to permit signal remultiplexing. The output of theinverse filter bank 420 a-N provides a set of inverse filtered samplestreams.

The inverse filtered sample streams at the output of the inverse filterbank 420 a-N are provided to the sample multiplexer 430. The samplemultiplexer 430 re-combines the samples, in a time multiplexing fashion,into a single sample stream. The sampling rate of the new single samplestream is preferably 2NF_(S) (F_(S) is the data rate of one channel).Clock signals representing both the input parallel sample stream rateand the new sampling rate at the output of the sample multiplexer 430are also provided.

In a preferred embodiment, the assembler 410 is realized as an inversetype IV DCT, and the filter bank 420 a-N is realized as an effectiveinverse bifurcated filter bank with respect to filter bank 330 a-N aspreviously described. In this and other possible approaches, advantagesexist due to the sparse matrix factorization stages containing a definedsparse inverse as well as the complementary form of the filteringstages. For example, the Type IV DCT is its own inverse i.e., (DCTIV)²=I (identity matrix), and the bifurcated filters work with thetransform elements to shape the bands of independent physical channels.Also, the inverse filter bank 420 a-N, shown as a bifurcated filterstructure has a signal splitting at its input for providing a crosscoupling of signals to the even and odd branches of the individualfilters. After each branch in the individual filters has completedprocessing, the even and odd branches of each individual filter aresummed together to form the individual output signal.

Alternatively, since the type IV DCT function in both the distributor350 and assembler 410 may be the same, only one block for bothoperations may be used. For example, a single block in conjunction witha signal multiplexer (not shown) may provide either a signalrepresenting the set of individual physical channels or the base set ofparallel data streams in alternating operations.

A controller 470 may connect to the assembler 410, filter bank 420 a-N,and sample multiplexer 430. The controller 470 may control the finalselection process and ordering of selected physical channels inassembler 410. The controller 470 may follow a pre-programmed allocationand ordering algorithm, or may process user inputs to determine theallocation and ordering. The controller 470 may also provide aninterface for user inputs or a communications input in order to receiveand convey the user requested channel information from multiplelocations. As described earlier, a home or customer premises may supplymore than one customer input. In addition, controller 470 may provideadditional functions for operation of the assembler 410, filter bank 420a-N, and multiplexer 430 such as clock functions, as necessary. Thecontroller 470 may also be embodied as a portion of a larger controllerfunction responsible for controlling and managing, for instance, theentire re-synthesizer device.

Additionally, if the M signals at the input to the assembler 410 areless than the N original channels, the channel re-combiner may alsochange the overall sampling rate. The assembler 410 may be reconfiguredto process the M signals in an M point transform, producing M paralleldata streams. The filter bank may subsequently contain only M branchesand the sample multiplexer process only M inputs. The clocks, suppliedto the D/A converter as well as other blocks with diagram 400 may alsobe a scaled version of the clock used for digital channel selector 230.For instance, if M is one half the number N, then the clock signal forthe digital channel re-combiner 240 may be one half the frequency of theclock signal for the digital channel selector 230. Note that the clocksignal supplied to the other blocks working on parallel data streams mayremain unaffected.

Further, the choice of value of M may be chosen for instance to permit amaximum of allowable channels at any time. However, in actual operation,a number less than M channels may actually be in use.

Turning now to FIG. 5, a block diagram 500 of a further embodiment ofthe present invention is shown. The diagram shows an implementation ofthe re-synthesizer 110 that includes digital signal processing andfurther includes program stream processing in order to increase theperformance and available bandwidth for selected channels. In order tofacilitate a further understanding of the invention, a re-synthesizer110 will be described here using only a single L-band signal as aninput. An input RF processing block 502 is connected to an A/D converter504. The output of the ND converter is connected to a digital channelselector 510. The outputs of the digital channel selector 510 eachindividually connect to a digital demodulator (demod) 520 a-M. Eachdigital demod 520 a-M connects to a transport demultiplexer demux) 530a-M. The outputs of each transport demux 530 a-M connect to a streaminsert and extract block 540. The outputs of the stream insert andextract block connect to a set of transport remultiplexer (remux) blocks560 a-N. Each transport remux 560 a-N connects to a digital modulator570 a-N. The outputs of the digital modulators 570 a-N connect into adigital channel re-combiner 580. The output of the digital channelre-combiner 580 connects into a D/A converter 592. The output of the D/Aconverter 593 connects into an output RF processing block 594. Acontroller 550 also connects to all of the other blocks including thestream insert and extract block 540.

The operation of blocks identified as input RF processing block 502, A/Dconverter 504, digital channel selector 510, digital channel re-combiner580, D/A converter 592, and output RF processing block 594 are similarin operation to blocks having the same name described previously. Exceptas noted, these blocks will not be further described.

The digital channel selector 510 provides a set of selected channels tothe digital demods 520 a-M. The digital demods 520 a-M contain digitalsignal processing for the demodulation, transmission equalization, anderror correction of the selected channels according to the requiredtransmission standard prescribed for the selected channel. In apreferred embodiment, digital demods 520 a-M include processingnecessary to demodulate and decode transport streams sent in eitherMotion Picture Entertainment Group standard MPEG 2 or Joint Video Team(JVT) format using either a Quaternary Phase Shift Keying (QPSK)modulation format or 8-PSK modulation format. The digital demods 520 a-Nalso perform error correction using either Viterbi, Reed Solomon, and/orLow Density Parity Check (LDPC) error correction techniques. Furtherdetails regarding the individual detailed operation of the digitaldemods 520 a-M are well known by those skilled in the art.

Each of the digital demods 520 a-M produces a transport streamrepresenting one or more individual program streams multiplexed withadditional identification data. As described previously, a transportstream contains one or more program streams usually in multiplexed andpacketized form. A program stream may represent an audio or video signalor may represent data such as a program guide. Each transport stream isprovided to one of the transport demuxes 530 a-M. The transport demuxes530 a-M process the transport streams by first recovering and separatingthe identification data for the transport stream. The transport demuxes530 a-N use the identification data or program identifiers (PIDs) toseparate out the program stream data in the transport stream intopackets for each of the individual program streams. The transportdemuxes 530 a-M assemble the packets into separate individual programstreams. The output of the transport demuxes 530 a-M may supply theindividual program streams on separate signal lines as shown, or mayalternately provide the program streams along with the PIDs over acommunications bus. In addition, stream identifiers are provided. Thesestream identifiers may include the PIDs supplied originally or mayinclude new identification information sent along with the programstreams. The stream identifiers may be used in further processingincluding reassembling the program streams back into transport streams.

The individual program streams are provided to the stream insert andextract block 540. The stream insert and extract block 540 allowsremoval and insertion of individual program streams into the set ofindividual streams present. The stream insert and extract block 540 maybe able to remove program streams that are not required at the outputand insert new program streams in place of the removed program streams.The new program streams may, for instance, represent content not presentin the original signal. In a preferred embodiment, the new programstream represents local advertising and news content inserted in placeof content in the original signal. The stream insert and extract block540 may also be able to remove or introduce more than one stream at atime, and may include the ability to remove or introduce segments ofprogram streams based on, for instance, time stamp identifiers presentwith the PIDs or stream identifiers.

The removal and insertion operations do not need to be matched andremoved program streams are not required to be replaced in completefashion by the insertion of new streams. However, the addition of newstreams may not be possible without removing existing program streams.The new program streams may utilize the stream identifier informationsuch as the PIDs from the removed program streams. Additionally, the PIDinformation may be modified in order to facilitate new program guidedata while the stream identifier may remain the same, in order to allowthe new program stream to be processed correctly downstream.

The stream insert and extract block 540 is controlled by controller 550.The controller 550 provides the signal management for the stream insertand extract block 540 as well as providing a signal path for removingand introducing the program streams. In addition, the controller 550provides connections to external circuitry (not shown) for supplying theremoved program streams to other devices, or for inputting the newprogram streams from other devices. The controller 550 also managesinputs provided by users either directly or remotely. The controller 550provides management of the program stream identifiers during theinsertion and extraction used in processing the program streams. Thecontroller 550 may also include the ability to generate and supply newprogram identification information including new program guide data foridentifying the new program streams.

The output of the insert and extract block 540 contains groups ofprogram streams that are provided to the transport remuxes 560 a-N. Thetransport remuxes 560 a-N process the groups of program streams, usingthe stream identifiers, and multiplex the streams back into remuxedtransport streams. These remixed transport streams include any newprogram streams that were added replacing the removed program streamsprocessed in the stream insert and extract block 540. In a preferredembodiment, streams. containing the stream identifiers originallygrouped in transport streams at the output of digital demods 520 a-M areremulitplexed together in each of the transport remuxes 560 a-N. As withthe program streams at the output of the transport muxes 530 a-M, theoutput of the insert and extract block 540 may supply the individualprogram streams on separate signal lines, as shown, or may alternatelyprovide the program streams along with the stream identifiers over acommunications bus. The transport remuxes 560 a-N process the individualprogram streams along with the stream identifiers to form a singlepacketized and multiplexed transport data stream containingidentification data and program stream information.

Each output of the transport remuxes 560 a-N is supplied to digitalmodulators 570 a-N. In the digital modulators 570 a-N, the transportstreams are transformed into digital communications signals. The digitalmodulators 570 a-N typically provide error correction processing toincorporate error correction into the signal. Additionally the digitalmodulators 570 a-N include data to symbol mapping for creating aparticular modulation signal format. In a preferred embodiment, digitalmodulators 570 a-N include processing necessary to code and modulatetransport streams for sending in either Motion Picture EntertainmentGroup standard (MPEG 2) or Joint Video Team (JVT) format using either aQuaternary Phase Shift Keying (QPSK) modulation format or an 8-PSKmodulation format. The digital modulators 570 a-N also generate andinsert error correction information using either Viterbi, Reed Solomon,and/or Low Density Parity Check (LDPC) error correction techniques.Further details regarding the individual detailed operation of thedigital modulators 570 a-N are well known by those skilled in the art.

It is important to note that the digital modulation format provided bythe digital modulators 570 a-N may be the same as the format used inprocessing the signals in the digital demods 520 a-M. However, themodulators 570 a-N may provide output signals in an alternate format,including formats such as 64 point Quadrature Amplitude Modulation(64QAM). It is important to note that the format chosen in modulator 570a-N may most likely match a format that can be processed in thedownstream customer equipment including settop boxes.

Turning now to FIG. 6, a block diagram 600 of another embodiment of thepresent invention is shown. FIG. 6 illustrates a three L-band signalinput re-synthesizer utilizing the inventive concept described herein.Each L-band input signal is processed through RF input processing, notshown.

The processed L-band input signals are connected to A/D converters 604a-c. The outputs of the A/D converters 604 a-c are connected to digitalchannel selectors 610 a-c. The outputs of the digital channel selectors610 a-c each individually connect to groups of digital demods 620 a1-aM, 620 b 1-bM, and 620 c 1-cM. Each of the digital demods 620 a 1-aM,620 b 1-bM, and 620 c 1-cM connects to groups of transport demuxes 630 a1-aM, 630 b 1-bM, and 630 c 1-cM. The one or more outputs of each of thetransport demuxes 630 a 1-aM, 630 b 1-bM, and 630 c 1-cM connects to atransport stream cross-multiplexer 640. The outputs of the transportstream cross-multiplexer 640 connect to a set of digital modulators 670a-N. The outputs of the digital modulators 670 a-N connect into adigital channel re-combiner 680. The output of the digital channelre-combiner 680 connects into a D/A converter 692. The output of the D/Aconverter 692 may connect to further RF processing (not shown) prior toproviding an output for transmitting on a coaxial cable. A controller650 also connects to all of the other blocks including the transportstream cross-multiplexer 640.

The operation of blocks identified as A/D converters 604 a-c, digitalchannel selectors 610 a-c, digital demods 620 a 1-aM, 620 b 1-bM, and620 c 1-cM, transport de-muxes 630 a 1-aM, 630 b 1-bM, and 630 c 1-cM,digital modulators 670 a-N, digital channel re-combiner 680, and D/Aconverter 692 are similar in operation to blocks having the same nameand described previously. Except as noted, these blocks will not befurther described.

Each digital channel selector 610 a-c is capable of producing M outputsrepresenting M physical channels where M is less than or equal to the Noriginal physical channels from an L-band signal. Each L-band signal mayprovide a different number of physical channels for eventual use in thefinal output signal as was described previously.

Each of the selected channels from digital channel selectors 610 a-c isthen further demodulated in the digital demod blocks 620 a 1-aM, 620 b1-bM, and 620 c 1-cM. The output transport streams are then processed inthe transport demuxes 630 a 1-aM, 630 b 1-bM, and 630 c 1-cM. Eachtransport demux 630 a 1-aM, 630 b 1-bM, and 630 c 1-cM. produce one ormore individual program streams along with stream identifiers asdescribed previously. The stream identification will permit furtherprocessing including the reassembling into a new transport streamdescribed below.

The individual programs streams, along with the stream identifiers, areprovided to the transport stream cross-multiplexer 640. The transportstream cross-multiplexer 640 allows programs streams from differenttransport originally streams to be combined or multiplexed together toform new transport streams. The transport stream cross-multiplexer 640further selects and groups the selected program streams for processingto form transport streams. Each group of selected program streams, alongwith the stream identifiers is packetized and further multiplexedtogether to form new transport streams. For example, program streams oneand two are requested from a particular channel delivered as a multiplexof channels from a first satellite but not a program stream three. Also,program stream one is requested from a particular channel delivered as amultiplex of channels from a second satellite, but not program streamstwo, three, and four. The transport stream cross-multiplexer 640 mayassign program stream one from the second satellite channel as programstream three of the first satellite channel and also make the necessarystream identification changes. The transport stream cross-multiplexer640 may then remultiplex the three program streams to create a newtransport stream.

The selected program streams and stream identifiers are re-multiplexedor packaged to permit more efficient delivery of the selected programcontent by the user. The number of new transport streams, N, may bedifferent from the number of transport streams that were supplied to thetransport stream cross-multiplexer 640. The number of transport streamsused is a matter of design choice, but may not exceed the number ofavailable channels in the final output signal. Further, as describedpreviously, the order of the transport streams may be changed by thetransport stream cross-multiplexer 640 from the order of the transportstreams provided by the digital demods 620 a 1-aM, 620 b 1-bM, and 620 c1-cM.

The transport stream cross-multiplexer 640 is controlled by controller650. The controller 650 provides the signal management for the transportstream cross-multiplexer 640 such as managing the packetization and timestamp indicators provided as part of the stream identification. Thecontroller also provides new stream identification information, forinstance, in the form of new PIDs. The new identification information isused in the formation of the new transport streams in the transportstream cross-mulitplexer 640. The controller 670 also manages inputsprovided by users, provided either directly or remotely. The controller670 may also include the ability to generate and supply new programidentification information including new program guide data foridentifying the program streams within the new transport streams.

Each of the new transport streams from the transport streamcross-multiplexer 640 is provided to the digital modulators 670 a-N. Asdescribed previously, the digital modulators 650 a-N modulate thetransport streams using a particular encoding and modulation format toform modulated channels of information. Additionally, the formatprovided by the modulator may be the same as the format used inprocessing the signals in the digital demods 620 a 1-aM, 620 b 1-bM, 620c 1-cM. However, the modulator may provide the output signals in analternate format, including formats such as 64 QAM. It is important tonote that the format chosen in the modulator should match a format thatcan be processed the downstream customer equipment such as settop boxesor other network equipment.

Each of the modulated channels from the digital modulators 670 a-N isprovided to the digital channel re-combiner 680. The digital channelre-combiner 680 may process up to N channels in its assembler block asdescribed above. The assembler in the digital channel re-combiner 680may also includes switching and selection circuits to manage which ofthe M inputs originally provided from each of the digital channelselectors 530 a-c are processed in the digital channel re-combiner 680.The management and switching function is controlled by the controller650.

The digital channel re-combiner 680 may also contain signal processingsuch as digital signal level adjustment applied to each of the selectedchannels. Level adjustment may allow all selected channels to bedelivered at approximately the same signal level improving theperformance of the home equipment.

Block diagram 600 forms a multi-input, single output channel selection,translation, stream processing, and distribution device. The deviceproduces an output of up to N channels in a single signal for deliveryover a single coaxial cable, from an input containing up to three timesN possible input channels presented in three separate signals. Theselected channels are then digitally demodulated to the bit packet leveland disassembled into program streams. The various program streams andtheir associated identifiers may then be re-combined into new physicalchannels, with new identifiers if needed, and digitally re-modulatedinto a single signal. The re-synthesizer would create a new cross-signalre-multiplexed RF output. The re-synthesizer allows collecting sets ofprograms to be simultaneously viewed on the same set of channels that isdifferent and more efficiently presented to the user than providing theoriginal set of signals. Note, that the use of three inputs isillustrative, and a greater or fewer number of inputs containing agreater or fewer number of possible input channels may be used.

It is also possible that the functions described in the stream insertand extract block 540 and the transport stream cross-multiplexer 640 maybe combined and used in the same re-synthesizer. For instance, in amulti-dwelling unit installation, the combined transportcross-multiplexer and stream insert and extract block may be used toprovide a signal containing program streams arranged into new channelsas requested by the various occupants of the dwelling units as well asprovide local community events in a program stream provided to alloccupants.

Turning now to FIG. 7, a flow chart 700 utilizing the present inventionis shown. At step 702, one or more incoming satellite signals arereceived by a device, such as the re-synthesizer described in blockdiagram 600. Next at 704, the one or more incoming satellite signals areconverted to digital signals. The conversion is preferably performed byA/D converters 604 a-c, and may further include processing forseparating the individual physical channels after the conversion such asdescribed in digital channel selectors 610 a-c. Next, at step 706, thedesired physical channels are selected to form a group of selectedfrequency channels. The selected frequency channels may be outputs fromdigital channel selectors 610 a-c. The selected frequency channels maybe selected in digital channel selectors 610 a-c based on requests bythe customer's home equipment. The selection process may be managed bycontroller 650. The controller 650 may be responsible for receiving andmanaging multiple requests and providing the proper information to thedigital channel selectors 610 a-c.

Next, at step 708, the selected digital channels are demodulated. Thedemodulation may occur in digital demods 620 a 1-aM, 620 b 1-bM, and 620c 1-cM. At step 710, the demodulated channels, now represented astransport streams, are demultiplexed into individual program streams.The demultiplexing may take place in the transport demuxes 630 a 1-aM,630 b 1-bM, and 630 c 1-cM. Next at step 712, the individual programstreams are processed to form new transport streams. Step 712 mayinvolve removing existing program streams and inserting new programs foruse in the in the new transport streams such as described in the streaminsert and extract block 540. Step 712 may also provide the ability tore-arrange and recombine the program streams to form new transportstreams such as described in transport stream cross-multiplexer 640.

Next, at step 714, the new transport streams are modulated into newchannels. The modulation may be accomplished in digital modulators 670a-N. The modulation format used in modulators 670 a-N may be the same asthe format the original L-band signals were provided in. However, theformat may also be different and may instead match a format that can beprocessed by downstream equipment such as settop boxes.

Next, at step 716, the group of new channels is re-combined in afrequency diverse manner to form a signal occupying a range offrequencies and containing the channels at separate frequencies. Therecombination may include a means for processing the group of selecteddigital channels such as described in digital channel re-combiner 680.At step 718, the recombined frequency diverse digital signal isconverted back into an analog signal containing the selected channels atseparate frequencies. The conversion may be performed in D/A converter692. Finally, at step 720, the analog signal, representing the selectedprogram streams from the selected channels is provided as an outputsupplied for transmission to other devices such as settop boxes and/orhome network equipment.

While the invention may be susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and have been described in detail herein. Theforegoing merely illustrates the principles of the invention and it willthus be appreciated that those skilled in the art will be able to devisenumerous alternative arrangements which, although not explicitlydescribed herein, embody the principles of the invention and are withinits spirit and scope. For example, although illustrated in the contextof separate functional elements, these functional elements may beembodied on one or more integrated circuits (ICs). Similarly, althoughshown as separate elements, any or all of the elements of may beimplemented in hardware, software, or a combination of both. It istherefore to be understood that numerous modifications may be made tothe illustrative embodiments and that other arrangements may be devisedwithout departing from the scope of the present invention as defined bythe appended claims.

1. An apparatus comprising: a receiver for receiving a plurality ofdigitally multiplexed signals, each digitally multiplexed signalassociated with a different physical transmission channel, and forsimultaneously recovering from at least two of the digital multiplexes aplurality of bit streams; and a transmitter for inserting the pluralityof bit streams into different digital multiplexes and for modulating thedifferent digital multiplexes for transmission on different transmissionchannels.
 2. The apparatus set forth in claim 1, wherein said receiverfurther comprises: a sampler for sampling the signal to provide aplurality of decimated sample streams; and a distributor operativelyconnected to said sampler for processing said plurality of decimatedsample streams to provide output signals representative of said one ormore different physical channels.
 3. The apparatus of claim 2, whereinsaid distributor includes a transform element.
 4. The apparatus of claim2, wherein said sampler further comprises: a demultiplexer fordemultiplexing the signal into said plurality of decimated samplestreams; and a plurality of filters connected to said demultiplexer forprocessing said plurality of decimated sample streams.
 5. The apparatusof claim 2, wherein said receiver further comprises a selectoroperatively connected to said distributor for selecting a subset ofoutput signals representative of said one or more different physicalchannels.
 6. The apparatus of claim 2, wherein said receiver furthercomprises a demodulator operatively coupled to said selector forprocessing said subset of output signals and generating said pluralityof bit streams.
 7. (canceled)
 8. The apparatus of claim 1, wherein saidtransmitter further comprises: a bit stream processor for processingsaid plurality of bit streams into said new digital multiplexes; and amodulator connected to said bit stream processor for modulating said newdigital multiplexes into a set of selected physical channels.
 9. Theapparatus of claim 8, wherein said bit stream processor includes aprocessor for inserting new bit streams into said new digitalmultiplexes not present in said plurality of digital multiplexes. 10.The apparatus of claim 8, wherein said bit stream processor includes aprocessor for re-arranging said bit streams between said plurality ofdigital multiplexes and said new digital multiplexes.
 11. The apparatusof claim 1, wherein said modulator is a modulator capable of modulatingsignals for reception by a satellite signal receiver.
 12. The apparatusof claim 1, wherein said transmitter further comprises: an assembleroperative on said selected physical channels to provide a set ofparallel data streams representing the combination of said selectedphysical channels; and a converter for converting said parallel datastreams into said different physical transmission channels.
 13. Theapparatus of claim 12, wherein said assembler includes a transformelement.
 14. The apparatus of claim 12, wherein said converter furthercomprises: a plurality of filters for processing said plurality ofparallel data streams; and a multiplexer connected to said plurality offilters for multiplexing said plurality of parallel data streams into asingle sample stream containing said different physical transmissionchannels.
 15. The apparatus of claim 1, wherein said differenttransmission channels are included in one signal.
 16. (canceled)
 17. Theapparatus of claim 1, wherein said plurality of bit streams include aplurality of program streams containing audio, video, or datainformation.
 18. A method for re-synthesizing signals comprising:receiving a first signal having a plurality of different program streamsin different frequency channels; selecting a set of program streams fromsaid plurality of different frequency channels; combining said set ofprogram streams to form a second signal; and transmitting said secondsignal.
 19. The method of claim 18, wherein the step of selectingfurther comprises: decimating said first signal into a plurality ofdecimated sample streams; performing a transform on said number ofdecimated sample streams to provide transform output signals.
 20. Themethod claim 19, wherein the step of decimating includes: demultiplexingthe signal into the number of decimated sample streams; and processingthe number of decimated sample streams with a plurality of filters formatching the discrete cosine transform.
 21. The method of claim 18,wherein the step of selecting includes re-ordering said set of programstreams.
 22. The method of claim 18, wherein the step of combiningfurther comprises: performing transform-based processing on said set ofdifferent frequency channels to provide a plurality of parallel datastreams; and processing said plurality of parallel data streams toprovide said second signal.
 23. An integrated circuit for use in areceiving system, which receives signals representing a plurality ofchannels, the integrated circuit comprising: a demultiplexing elementfor demultiplexing a received sampled signal to produce a plurality offirst data streams; a transform element for transforming said pluralityof first data streams into a plurality of transform output signals, andfor transforming at least two of said plurality of transform outputsignals into a plurality of second data streams; a bit stream processingelement for processing said plurality of transform output signals toselect a set of bit streams and to combine said selected bit streamsinto said at least two transform output signals; and a multiplexingelement for mulitplexing said plurality of second data streams andoutputting a sampled signal.
 24. The integrated circuit of claim 23,wherein said transform element uses a type IV discrete cosine transform.25. The integrated circuit of claim 23, further comprising: a firstfilter element operative to filter said plurality of first data streamsprior to providing said plurality of first data streams to saidtransform element; and a second filter element operative to filter saidplurality of second data streams prior to providing said plurality ofsecond data streams to said multiplexing element.
 26. The integratedcircuit of claim 23, further comprising: a demodulator element fordemodulating said plurality of transform output signals prior toproviding said plurality of transform output signals to said bit streamprocessing element; and a modulator element for modulating said at leasttwo transform output signals prior to providing said least two transformoutput signals to said transform element.
 27. An apparatus forre-synthesizing signals comprising: means for receiving a first signalhaving a plurality of bit streams from different frequency channels;means for translating said first signal into a set of signalsrepresenting said plurality of different frequency channels; means forselecting a set of bit streams from said set of signals; means forcombining said set of bit streams to form a second signal; and means fortransmitting said second signal.